Your car’s brake lights play an important safety role by alerting other drivers when you are slowing down or stopping. But what if those brake lights stay illuminated even when you aren’t braking? This is usually an indication of a problem with your car’s braking system that requires prompt attention. So how long is it safe to drive with your brake light stuck on?
Understanding Brake Light Functions
Brake lights, also known as stop lamps, are red lights mounted on the rear of your vehicle that illuminate when you press on the brake pedal. They alert other drivers that you are slowing down or coming to a stop.
Most cars have two brake lights, one on each side of the rear. Some larger vehicles like trucks may have three brake lights. These lights are powered through the brake pedal switch, which completes the circuit when the pedal is pressed.
In addition to the standard brake lights, most modern cars also have a third high-mounted brake light located towards the rear window. This light provides added visibility to drivers behind you.
How the Brake Light Works
When you press the brake pedal, it activates a switch that completes the electrical circuit for the brake lights. This switch is mounted on or near the brake pedal.
Pressing the pedal pushes the switch closed, allowing power to flow from the battery to the lights. The actual brake lights are illuminated by bulbs or LED arrays mounted in the light housing.
In a hydraulic brake system, the pedal lever arm activates pistons in the master cylinder to push brake fluid through the lines to each wheel cylinder. The pressure applied to the calipers or brake shoes slows your car.
- Brake pedal and switch
- Bulbs/LED arrays in light housings
- Wiring from switch to lights
- Fuse or circuit breaker
- Brake fluid reservoir
When everything is working properly, the brake lights come on quickly when you brake, providing maximum visibility. They turn off when you release the pedal.
Common Causes of a Stuck Brake Light
There are a few common mechanical issues that can cause your brake light to stay on even when you are not braking:
1. Faulty Brake Light Switch
The most common cause of a stuck brake light is a malfunctioning brake light switch. This switch is designed to activate the lights only while the pedal is depressed. If the switch fails in the closed position, the lights will remain on at all times.
A faulty switch can occur due to wear, damage, or contamination. Replacing the faulty switch will resolve the stuck brake light in this case.
2. Brake Pedal Binding
The brake pedal arm pressing against the switch is what illuminates the brake lights. If something is causing the brake pedal to stick or bind so it cannot fully retract, the switch will stay activated.
Causes of pedal binding include:
- Accumulated debris, dirt or grease preventing pedal motion
- A loose, worn or damaged bushing/fastener
- Sticky pivot points
- Blocked return spring
Fixing the source of brake pedal binding will allow it to properly retract and turn the lights off.
3. Low Brake Fluid
As brake pads wear down, brake fluid level drops gradually in the master cylinder reservoir. If fluid gets too low, it allows more pedal travel before the brakes engage.
This extra pedal motion keeps the switch engaged even at rest. Topping off the brake fluid to the proper level will help retract the pedal and switch fully.
4. Malfunctioning Brake Light Relay
Some vehicles have a relay or control module that activates the brake lights instead of a simple switch. If this relay or module malfunctions, it could turn the lights on and leave them on. Replacing the relay will be needed in this situation.
5. Electrical Short
Damaged or faulty wiring that shorts between the brake light circuit and power source can also cause lights to remain illuminated. Inspect wires and connectors for damage, moisture, fraying, etc. Repair or replace problematic wiring as needed.
Dangers of Driving with Stuck Brake Light
A stuck brake light might seem like a minor annoyance, but driving with your brake lights continuously on can be dangerous for a few reasons:
- Reduced braking reactions from other drivers – Since your brake lights are always on, other motorists may not react as quickly when you actually brake since they are desensitized. Their slower response time could increase chances of a rear-end collision.
- Mixed signaling to other drivers – Illuminated brake lights could confuse other drivers when you accelerate or turn without braking. This mixed signaling could lead to improper reactions.
- Increased chances of accidents – With degraded braking reactions from other drivers, you are at higher risk for accidents in emergencies when you need to brake suddenly.
- Masking brake problems – A stuck brake light could also hide problems with your brakes themselves. You won’t have the warning of brake lights not coming on when they should.
- Draining the battery – Brake lights draw significant electrical load. If stuck on continuously, they could drain the battery and lead to further issues.
To avoid these dangers, any stuck brake light situation needs prompt diagnosis and repair.
How Long is it Safe to Drive?
When you first notice your brake light stuck on, how long can you safely continue driving before getting it fixed? There are a few factors to consider when deciding if and how long you can drive with an illuminated brake light:
- Has the light been stuck long? – If you just noticed the light but aren’t sure how long it’s been on, assume a short period and proceed cautiously. The longer it’s been stuck on undetected, the more risk involved.
- What is the cause? – Consider the potential causes. A simple faulty switch may be lower risk than a major brake fluid leak or electrical short, for example. Assess the likely issue and risks.
- Type of driving expected – Driving short distances in light traffic is far lower risk than highway driving in heavy traffic. Know the conditions you’ll encounter.
- Overall brake performance – Do the brakes feel normal otherwise? Any signs of reduced performance or issues? Assess your brake operation.
- Ability to use signals – Can you signal turns and lane changes to compensate for reduced brake light communication?
If the light has been stuck for a short period, the cause seems to be a minor failure, conditions are safe, and brakes are normal, you might drive for a few days until it can be repaired. But exercise extreme caution in the interim and monitor brake operation closely.
However, if the light has been on awhile, the cause is unknown, conditions are risky, or brakes seem compromised – stop driving and have it repaired immediately. Don’t take chances with your safety.
How to Diagnose and Fix a Stuck Brake Light
If you find yourself with a stuck brake light, follow these steps to diagnose and repair the issue:
1. Inspect the brake pedal
With the engine off, press the pedal a few times and make sure it is retracting fully when released. Listen for any grinding, binding or sticking. If it’s not returning properly, identify the source of binding.
2. Check brake light switch
Locate the switch mounted near the brake pedal. With pedal at rest, use a multimeter to check if switch is closed and allowing current flow. If closed, switch is faulty.
3. Check brake fluid level
Look at the reservoir level. If very low, topping it off may allow pedal/switch to retract fully. Note: Low fluid could indicate leaks or worn pads.
4. Electrical troubleshooting
If switch tests ok but light stays on, check fuses, wiring condition, relay operation per your repair manual. Look for shorts, damage, loose connections.
5. Test operation
Once repairs are made, test the lights. Press pedal and make sure lights activate. When pedal is released, lights should go off. Confirm proper operation.
6. Investigate if problem persists
If lights still stay on after repairs, further diagnosis is required. There may be additional underlying issues with brakes or electrical. Seek professional help.
Be methodical in your troubleshooting. Don’t ignore a stuck brake light or simply disconnect it, as this compromises safety. Identify the failure and make proper repairs for reliable and safe operation.
Maintaining Your Brakes and Lights
To avoid becoming stranded with a stuck brake light or other brake problems, it’s important to maintain your brakes proactively:
- Inspect brake system regularly – Check brake lines, hoses, fluid levels/condition, pads, rotors, switch function. Look for leaks, damage, and wear.
- Change brake fluid regularly – Fluid should be flushed every 2 years or 24,000 miles. It absorbs moisture over time which reduces effectiveness.
- Replace worn parts on schedule – Have worn pads, rotors, and other components replaced as needed to keep brakes in top shape.
- Check brake lights monthly – Test brake light operation monthly to catch any issues early. Scan for moisture, damage, corrosion.
- Address problems promptly – At first sign of issues like illumination without braking, have the cause diagnosed and repaired immediately.
Proactive brake system care reduces the chances of being caught off guard by a stuck brake light or any brake failure when you need them most.
Frequently Asked Questions
How do I know if my brake light is stuck on?
Check the reflection in a window or ask someone to look at the rear of your car. If the brake lights are red and illuminated when your foot is off the brake pedal, they are stuck on.
What should I do if my brake and ABS lights are both on?
If both brake and ABS warning lights are illuminated, there is likely a major issue with the hydraulic brake system. Stop driving immediately and have your brakes checked out. Don’t drive until the issue is resolved.
Why does my brake pedal pulse when I stop sometimes?
This pulsing sensation is caused by the ABS system activating to prevent wheel lockup during hard braking. It’s normal and an indication the ABS is working properly. Continue pressing the pedal through the pulses.
How often should brake pads be replaced?
Most brake pads last 30,000 – 70,000 miles before needing replacement. Have them inspected regularly and replaced when worn to avoid damage to rotors and reduced braking ability.
Can I just take the bulb out of a stuck brake light?
No, you should never remove or disable a brake light bulb. This is unsafe and likely illegal. Instead, properly diagnose and repair the cause of the stuck light.
Driving with your brake lights illuminated even when you aren’t braking is a dangerous situation that should be addressed immediately. While you may be able to drive briefly with a stuck light in a low-risk scenario, it’s generally recommended to stop driving and seek repair as soon as possible.
The issue is typically caused by a faulty switch or relay, binding brake pedal, low brake fluid or an electrical issue. By methodically diagnosing the cause and making proper repairs, you can get your brake lights working properly again and keep driving safely. Making brake system maintenance a priority will also help avoid being caught off guard by a stuck light.